Surgical instrument with tissue density sensing

ABSTRACT

An apparatus comprises an end effector, a body assembly, a power source, and a control module. The end effector is operable for use in a surgical procedure and can deliver energy to a surgical site. The end effector comprises at least one sensor. The sensor is able to measure at least one physical characteristic associated with the surgical site. The body assembly is in communication with the end effector. The power source is in communication with the body assembly and is operable to deliver power to the end effector. The control module is in communication with the sensor and is operable to change delivery of power to the end effector based on data from the sensor indicating a change in tissue density.

BACKGROUND

In some settings, endoscopic surgical instruments may be preferred overtraditional open surgical devices since a smaller incision may reducethe post-operative recovery time and complications. Consequently, someendoscopic surgical instruments may be suitable for placement of adistal end effector at a desired surgical site through a cannula of atrocar. These distal end effectors may engage tissue in a number of waysto achieve a diagnostic or therapeutic effect (e.g., endocutter,grasper, cutter, stapler, clip applier, access device, drug/gene therapydelivery device, and energy delivery device using ultrasound, RF, laser,etc.). Endoscopic surgical instruments may include a shaft between theend effector and a handle portion, which is manipulated by theclinician. Such a shaft may enable insertion to a desired depth androtation about the longitudinal axis of the shaft, thereby facilitatingpositioning of the end effector within the patient.

Examples of endoscopic surgical instruments include those disclosed inU.S. Pat. Pub. No. 2006/0079874, entitled “Tissue Pad for Use with anUltrasonic Surgical Instrument,” published Apr. 13, 2006, the disclosureof which is incorporated by reference herein; U.S. Pat. Pub. No.2007/0191713, entitled “Ultrasonic Device for Cutting and Coagulating,”published Aug. 16, 2007, the disclosure of which is incorporated byreference herein; U.S. Pat. Pub. No. 2007/0282333, entitled “UltrasonicWaveguide and Blade,” published Dec. 6, 2007, the disclosure of which isincorporated by reference herein; U.S. Pat. Pub. No. 2008/0200940,entitled “Ultrasonic Device for Cutting and Coagulating,” published Aug.21, 2008, the disclosure of which is incorporated by reference herein;U.S. Pat. Pub. No. 2011/0015660, entitled “Rotating Transducer Mount forUltrasonic Surgical Instruments,” published Jan. 20, 2011, and issuedJun. 11, 2013 as U.S. Pat. No. 8,461,744, the disclosure of which isincorporated by reference herein; U.S. Pat. No. 6,500,176, entitled“Electrosurgical Systems and Techniques for Sealing Tissue,” issued Dec.31, 2002, the disclosure of which is incorporated by reference herein;and U.S. Pat. Pub. No. 2011/0087218, entitled “Surgical InstrumentComprising First and Second Drive Systems Actuatable by a Common TriggerMechanism,” published Apr. 14, 2011, now U.S. Pat. No. 8,939,974, issuedon Jan. 27, 2015, the disclosure of which is incorporated by referenceherein. Additionally, such surgical tools may include a cordlesstransducer such as that disclosed in U.S. Pat. Pub. No. 2009/0143797,entitled “Cordless Hand-held Ultrasonic Cautery Cutting Device,”published Jun. 4, 2009, and issued Apr. 16, 2013 as U.S. Pat. No.8,419,757, the disclosure of which is incorporated by reference herein.In addition, the surgical instruments may be used, or adapted for use,in robotic-assisted surgery settings such as that disclosed in U.S. Pat.No. 6,783,524,entitled “Robotic Surgical Tool with UltrasoundCauterizing and Cutting Instrument,” issued Aug. 31, 2004, thedisclosure of which is incorporated by reference herein.

While a variety of surgical instruments have been made and used, it isbelieved that no one prior to the inventor(s) has made or used aninvention as described herein.

BRIEF DESCRIPTION OF THE DRAWINGS

While the specification concludes with claims which particularly pointout and distinctly claim the invention, it is believed the presentinvention will be better understood from the following description ofcertain examples taken in conjunction with the accompanying drawings, inwhich like reference numerals identify the same elements and in which:

FIG. 1 depicts a block diagram view of an exemplary surgical instrument;

FIG. 2 depicts a perspective view of an exemplary ultrasonic surgicalinstrument;

FIG. 3 depicts a block schematic of an exemplary surgical instrument;

FIG. 4 depicts a flowchart diagram of an exemplary method of using thesurgical instrument of FIG. 3;

FIG. 5 depicts a flowchart diagram of an alternative exemplary method ofusing the surgical instrument of FIG. 3;

FIG. 6 depicts a flowchart diagram of yet another alternative exemplarymethod of using the surgical instrument of FIG. 3;

FIG. 7 depicts a flowchart diagram of yet another alternative exemplarymethod of using the surgical instrument of FIG. 3;

FIG. 8 depicts a flowchart diagram of yet another alternative exemplarymethod of using the surgical instrument of FIG. 3;

FIG. 9 depicts a flowchart diagram of yet another alternative exemplarymethod of using the surgical instrument of FIG. 3; and

FIG. 10 depicts a flowchart diagram of yet another alternative exemplarymethod of using the surgical instrument of FIG. 3;

The drawings are not intended to be limiting in any way, and it iscontemplated that various embodiments of the invention may be carriedout in a variety of other ways, including those not necessarily depictedin the drawings. The accompanying drawings incorporated in and forming apart of the specification illustrate several aspects of the presentinvention, and together with the description serve to explain theprinciples of the invention; it being understood, however, that thisinvention is not limited to the precise arrangements shown.

DETAILED DESCRIPTION

The following description of certain examples of the invention shouldnot be used to limit the scope of the present invention. Other examples,features, aspects, embodiments, and advantages of the invention willbecome apparent to those skilled in the art from the followingdescription, which is by way of illustration, one of the best modescontemplated for carrying out the invention. As will be realized, theinvention is capable of other different and obvious aspects, all withoutdeparting from the invention. For example, while various. Accordingly,the drawings and descriptions should be regarded as illustrative innature and not restrictive.

It is further understood that any one or more of the teachings,expressions, embodiments, examples, etc. described herein may becombined with any one or more of the other teachings, expressions,embodiments, examples, etc. that are described herein. Thefollowing-described teachings, expressions, embodiments, examples, etc.should therefore not be viewed in isolation relative to each other.Various suitable ways in which the teachings herein may be combined willbe readily apparent to those of ordinary skill in the art in view of theteachings herein. Such modifications and variations are intended to beincluded within the scope of the claims.

I. Overview of Exemplary Surgical Instrument

FIG. 1 shows components of an exemplary medical device and/or surgicalinstrument (10) in diagrammatic block form. As shown, medical device(10) comprises a control module (12), a power source (14), and an endeffector (16). Merely exemplary power sources (14) may include NiMHbatteries, Li-ion batteries (e.g., prismatic cell type lithium ionbatteries, etc.), Ni-Cad batteries, or any other type of power source asmay be apparent to one of ordinary skill in the art in light of theteachings herein. Control module (12) may comprise a microprocessor, anapplication specific integrated circuit (ASIC), memory, a printedcircuit board (PCB), a storage device (such as a solid state drive orhard disk), firmware, software, or any other suitable control modulecomponents as will be apparent to one of ordinary skill in the art inlight of the teachings herein. Control module (12) and power source (14)are coupled by an electrical connection (22), such as a cable and/ortraces in a circuit board, etc., to transfer power from power source(14) to control module (12). Alternatively, power source (14) may beselectively coupled to control module (12). This allows power source(14) to be detached and removed from medical device (10), which mayfurther allow power source (14) to be readily recharged or reclaimed forresterilization and reuse. In addition or in the alternative, controlmodule (12) may be removed for servicing, testing, replacement, or anyother purpose as will be apparent to one of ordinary skill in the art inview of the teachings herein. Control module (12) may also be operableto provide pulsing energy through use of power source (14) as will bediscussed further below.

End effector (16) is coupled to control module (12) by anotherelectrical connection (22). End effector (16) is configured to perform adesired function of medical device (10). By way of example only, suchfunction may include cauterizing tissue, ablating tissue, severingtissue, ultrasonically vibrating, stapling tissue, or any other desiredtask for medical device (10). End effector (16) may thus include anactive feature such as an ultrasonic blade, a pair of clamping jaws, asharp knife, a staple driving assembly, a monopolar RF electrode, a pairof bipolar RF electrodes, a thermal heating element, and/or variousother components. End effector (16) may also be removable from medicaldevice (10) for servicing, testing, replacement, or any other purpose aswill be apparent to one of ordinary skill in the art in view of theteachings herein. In some versions, end effector (16) is modular suchthat medical device (10) may be used with different kinds of endeffectors (e.g., as taught in U.S. Provisional Application Ser. No.61/410,603, etc.). Various other configurations of end effector (16) maybe provided for a variety of different functions depending upon thepurpose of medical device (10) as will be apparent to those of ordinaryskill in the art in view of the teachings herein. Similarly, other typesof components of a medical device (10) that may receive power from powersource (14) will be apparent to those of ordinary skill in the art inview of the teachings herein.

Medical device (10) of the present example includes a trigger (18) and asensor (20), though it should be understood that such components aremerely optional. Trigger (18) is coupled to control module (12) andpower source (14) by electrical connection (22). Trigger (18) may beconfigured to selectively provide power from power source (14) to endeffector (16) (and/or to some other component of medical device (10)) toactivate medical device (10) when performing a procedure. Sensor (20) isalso coupled to control module (12) by an electrical connection (22) andmay be configured to provide a variety of information to control module(12) during a procedure. By way of example only, such configurations mayinclude sensing a temperature at end effector (16) or determining theoscillation rate of end effector (16). Data from sensor (20) may beprocessed by control module (12) to effect the delivery of power to endeffector (16) (e.g., in a feedback loop, etc.). Various otherconfigurations of sensor (20) may be provided depending upon the purposeof medical device (10) as will be apparent to those of ordinary skill inthe art in view of the teachings herein. Of course, as with othercomponents described herein, medical device (10) may have more than onesensor (20), or sensor (20) may simply be omitted if desired. Furtherdetail regarding sensor (20) and variations thereof will be discussedbelow.

II. Exemplary Ultrasonic Surgical Instrument

FIG. 2 shows a surgical system (11), which includes an exemplaryultrasonic version (50) of instrument (10) described above. Whenultrasonic components of instrument (50) are inactive, tissue can bereadily gripped and manipulated, as desired, without tissue cutting.When the ultrasonic components are activated, instrument (50) permitstissue to be gripped by end effector (80) for coupling with theultrasonic energy to effect tissue coagulation, with application ofincreased pressure efficiently effecting tissue cutting and coagulation.If desired, ultrasonic energy can be applied to tissue without use ofthe clamping mechanism of end effector (80) by appropriate manipulationof the ultrasonic blade (82).

By way of example only, surgical system (11) may be constructed and/oroperable in accordance with any suitable teachings or combinations ofteachings from any of the following: U.S. Pat. No. 7,738,971 entitled“Post-Sterilization Programming of Surgical Instruments,” issued Jun.15, 2010, the disclosure of which is incorporated by reference herein;U.S. Pub. No. 2006/0079874 entitled “Tissue Pad for Use with anUltrasonic Surgical Instrument,” published Apr. 13, 2006, the disclosureof which is incorporated by reference herein; U.S. Pub. No. 2007/0191713entitled “Ultrasonic Device for Cutting and Coagulating,” published Aug.16, 2007, the disclosure of which is incorporated by reference herein;U.S. Pub. No. 2007/0282333 entitled “Ultrasonic Waveguide and Blade,”published Dec. 6, 2007, the disclosure of which is incorporated byreference herein; U.S. Pub. No. 2008/0200940 entitled “Ultrasonic Devicefor Cutting and Coagulating,” published Aug. 21, 2008, the disclosure ofwhich is incorporated by reference herein; U.S. Pat. Pub. No.2009/0143797, entitled “Cordless Hand-held Ultrasonic Cautery CuttingDevice,” published Jun. 4, 2009, and issued Apr. 16, 2013 as U.S. Pat.No. 8,419,757, the disclosure of which is incorporated by referenceherein; U.S. Pub. No. 2009/0209990 entitled “Motorized Surgical Cuttingand Fastening Instrument Having Handle Based Power Source,” publishedAug. 20, 2009, now U.S. Pat. No. 8,657,174, issued on Feb. 25, 2014, thedisclosure of which is incorporated by reference herein; U.S. Pub. No.2010/0069940 entitled “Ultrasonic Device for Fingertip Control,”published Mar. 18, 2010, now U.S. Pat. No. 9,023,071, issued on May 5,2015, the disclosure of which is incorporated by reference herein; andU.S. Pub. No. 2011/0015660, entitled “Rotating Transducer Mount forUltrasonic Surgical Instruments,” published Jan. 20, 2011, and issuedJun. 11, 2013 as U.S. Pat. No. 8,461,744, the disclosure of which isincorporated by reference herein. Similarly, various ways in whichmedical devices may be adapted to include a portable power source aredisclosed in U.S. Provisional Application Serial No. 61/410,603, filedNov. 5, 2010, entitled “Energy-Based Surgical Instruments,” thedisclosure of which is incorporated by reference herein.

Exemplary ultrasonic surgical system (11) comprises an ultrasonicsurgical instrument (50), a generator (21), and a cable (30) operable tocouple generator (21) to surgical instrument (50). A suitable generator(21) is the GEN 300 sold by Ethicon Endo-Surgery, Inc. of Cincinnati,Ohio. By way of example only, generator (21) may be constructed inaccordance with the teachings of U.S. Pub. No. 2011/0087212, entitled“Surgical Generator for Ultrasonic and Electrosurgical Devices,”published Apr. 14, 2011, now U.S. Pat. No. 8,986,302, issued on Mar. 24,2015, the disclosure of which is incorporated by reference herein. Itshould be noted that surgical instrument (50) will be described inreference to an ultrasonic surgical instrument; however, the technologydescribed below may be used with a variety of surgical instruments,including, but not limited to, endocutters, graspers, cutters, staplers,clip appliers, access devices, drug/gene therapy delivery devices, andenergy delivery devices using ultrasound, RF, laser, etc., and/or anycombination thereof as will be apparent to one of ordinary skill in theart in view of the teachings herein. Moreover, while the present examplewill be described in reference to a cable-connected surgical instrument(50), it should be understood that surgical instrument (50) may beadapted for cordless operation, such as that disclosed in U.S. Pat. Pub.No. 2009/0143797 (issued Apr. 16, 2013 as U.S. Pat. No. 8,419,757).Furthermore, surgical device (50) may also be used, or adapted for use,in robotic-assisted surgery settings such as that disclosed in U.S. Pat.No. 6,783,524.

Surgical instrument (50) of the present example includes a multi-piecehandle assembly (60), an elongated transmission assembly (70), and atransducer (100). Transmission assembly (70) is coupled to multi-piecehandle assembly (60) at a proximal end of transmission assembly (70) andextends distally from multi-piece handle assembly (60). In the presentexample transmission assembly (70) is configured to be an elongated,thin tubular assembly for endoscopic use, but it should be understoodthat transmission assembly (70) may alternatively be a short assembly,such as those disclosed in U.S. Pat. Pub. No. 2007/0282333 and U.S. Pat.Pub. No. 2008/0200940. Transmission assembly (70) of the present examplecomprises an outer sheath (72), an inner tubular actuating member (notshown), a waveguide (not shown), and an end effector (80) located on thedistal end of transmission assembly (70). In the present example, endeffector (80) comprises a blade (82) coupled to the waveguide, a clamparm (84) operable to pivot at the proximal end of transmission assembly(70), and, optionally, one or more clamp pads (86) coupleable to clamparm (84). It should also be understood that clamp arm (84) andassociated features may be constructed and operable in accordance withat least some of the teachings of U.S. Pat. No. 5,980,510, entitled“Ultrasonic Clamp Coagulator Apparatus Having Improved Clamp Arm PivotMount,” issued Nov. 9, 1999, the disclosure of which is incorporated byreference herein. It should also be understood that some versions of endeffector (80) may lack clamp arm (84). For instance, end effector (80)may simply include blade (82). The waveguide, which is adapted totransmit ultrasonic energy from a transducer (100) to blade (82), may beflexible, semi-flexible, or rigid. One merely exemplary ultrasonictransducer (100) is Model No. HP054, sold by Ethicon Endo-Surgery, Inc.of Cincinnati, Ohio. The waveguide may also be configured to amplify themechanical vibrations transmitted through the waveguide to blade (82) asis well known in the art. The waveguide may further have features tocontrol the gain of the longitudinal vibration along the waveguide andfeatures to tune the waveguide to the resonant frequency of the system.

In the present example, the distal end of the blade (82) is disposednear an anti-node in order to tune the acoustic assembly to a preferredresonant frequency f_(o) when the acoustic assembly is not loaded bytissue. When transducer (100) is energized, the distal end of blade (82)is configured to move longitudinally in the range of, for example,approximately 10 to 500 microns peak-to-peak, and preferably in therange of about 20 to about 200 microns at a predetermined vibratoryfrequency f_(o) of, for example, 55.5 kHz. When transducer (100) of thepresent example is activated, these mechanical oscillations aretransmitted through the waveguide to end effector (80). In the presentexample, blade (82), being coupled to the waveguide, oscillates at theultrasonic frequency. Thus, when tissue is secured between blade (82)and clamp arm (84), the ultrasonic oscillation of blade (82) maysimultaneously sever the tissue and denature the proteins in adjacenttissue cells, thereby providing a coagulative effect with relativelylittle thermal spread. An electrical current may also be providedthrough blade (82) and clamp arm (84) to also cauterize the tissue.While some configurations for transmission assembly (70) and transducer(100) have been described, still other suitable configurations fortransmission assembly (70) and transducer (100) will be apparent to oneor ordinary skill in the art in view of the teachings herein.

Multi-piece handle assembly (60) of the present example comprises amating housing portion (62) and a lower portion (64). Mating housingportion (62) is configured to receive transducer (100) at a proximal endof mating housing portion (62) and to receive the proximal end oftransmission assembly (70) at a distal end of mating housing portion(62). An aperture is provided on the distal end of mating housingportion (62) for insertion of various transmission assemblies (70). Arotation knob (66) is shown in the present example to rotatetransmission assembly (70) and/or transducer (100), but it should beunderstood that rotation knob (66) is merely optional. Lower portion(64) of multi-piece handle assembly (60) includes a trigger (68) and isconfigured to be grasped by a user using a single hand. One merelyexemplary alternative configuration for lower portion (64) is depictedin FIG. 1 of U.S. Pat. Pub. No. 2011/0015660, now U.S. Pat. No.8,461,744, issued on Jun. 11, 2013. Toggle buttons (not shown) may belocated on a distal surface of lower portion (64) and may be operable toactivate transducer (100) at different operational levels usinggenerator (21). For instance, a first toggle button may activatetransducer (100) at a maximum energy level while a second toggle buttonmay activate transducer (100) at a minimum, non-zero energy level. Ofcourse, the toggle buttons may be configured for energy levels otherthan a maximum and/or minimum energy level as will be apparent to one ofordinary skill in the art in view of the teachings herein. Moreover, thetoggle buttons may be located anywhere else on multi-piece handleassembly (60), on transducer (100), and/or remote from surgicalinstrument (50), and any number of toggle buttons may be provided. Whilemulti-piece handle assembly (60) has been described in reference to twodistinct portions (62, 64), it should be understood that multi-piecehandle assembly (60) may be a unitary assembly with both portions (62,64) combined. Multi-piece handle assembly (60) may alternatively bedivided into multiple discrete components, such as a separate triggerportion (operable either by a user's hand or foot) and a separate matinghousing portion (62). The trigger portion may be operable to activatetransducer (100) and may be remote from mating housing portion (62).Multi-piece handle assembly (60) may be constructed from a durableplastic (such as polycarbonate or a liquid crystal polymer), ceramicsand/or metals or any other suitable material as will be apparent to oneof ordinary skill in the art in view of the teachings herein. Stillother configurations for multi-piece handle assembly (60) will beapparent to those of ordinary skill in the art in view of the teachingsherein. For instance, instrument (50) may be operated as part of arobotic system. Other configurations for multi-piece handle assembly(60) will also be apparent to those of ordinary skill in the art in viewof the teachings herein.

Still other suitable forms that system (11) may take will be apparent tothose of ordinary skill in the art in view of the teachings herein.

III. Exemplary Surgical Instrument with Acoustic Sensing

It will be appreciated that as a surgical instrument (50) is used,surgical instrument (50) may encounter tissues of different densities.For instance, surgical instrument (50) may encounter different densitieswhen transitioning between muscle, bone, fat, scar tissue, or any othertype of tissue. It may be desirable to know when surgical instrument(50) encounters a change in tissue density during use of surgicalinstrument (50) in tissue. In some cases, it may be sufficient to knowthat a different tissue density is being encountered. It may also bedesirable to know the nature of the different types of tissue.Furthermore, in some situations, once a different tissue density isreached it will be appreciated that it may be desirable to have surgicalinstrument (50) automatically change its behavior. In addition or in thealternative, the user may be notified in some manner that surgicalinstrument (50) is nearing or is in contact with a different type oftissue where the user may decide to manually change his/her operation ofsurgical instrument (50).

FIG. 3 shows a schematic diagram of an exemplary surgical instrument(200) having a hand piece (202) in communication with an end effector(204). It should be understood that surgical instrument (200) is avariation of surgical instruments (10, 50) described above. End effector(204) is selectively in communication with hand piece (202), but it willbe appreciated that end effector (204) in some versions may beintegrally formed with hand piece (202). Other suitable configurationsmay be used as would be apparent to one of ordinary skill in the art inview of the teachings herein. End effector (204) comprises a variety ofcomponents including at least one microphone (210), at least one sensor(212), and at least one accelerometer (208). Of course, end effector(204) may include a variety of other components, including but notlimited to, an ultrasonic blade, a clamp arm, electrosurgical features,a staple applying assembly, etc. In versions where end effector (204)includes an ultrasonic blade, end effector may lack a clamping member.For instance, end effector (204) may be configured in accordance with atleast some of the teachings of U.S. Pat. Pub. No. 2008/0200940, thedisclosure of which is incorporated by reference herein. Other suitableforms that a blade-only end effector (204) may take will be apparent tothose of ordinary skill in the art in view of the teachings herein. Inversions of end effector (204) that include an ultrasonic blade and aclamping member, end effector (204) may be configured in accordance withat least some of the teachings of U.S. Pat. Pub. No. 2007/0191713, U.S.Pat. Pub. No. 2007/0282333, and/or U.S. Pat. Pub. No. 2006/0079874, thedisclosure of each of which is incorporated by reference herein. Othersuitable forms that end effector (204) may take will be apparent tothose of ordinary skill in the art in view of the teachings herein.

While end effector (204) of the present example comprises microphone(210), sensor (212), and accelerometer (208), it will be appreciatedthat end effector (204) need not necessarily contain each of microphone(210), sensor (212), and accelerometer (208). Furthermore, while FIG. 3depicts microphone (210), sensor (212), and accelerometer (208) as beingseparate from end effector (204), it will be appreciated that any or allof microphone (210), sensor (212), and accelerometer (208) may beintegrated into end effector (204) or in the alternative may beconstructed unitarily with end effector (204). It will be understoodthat microphone (210) and/or accelerometer (208) could be positioned inhand piece (202). For example, microphone (210) could be positioned suchthat microphone (210) is operable to monitor acoustic signals at theproximal end of a harmonic waveguide in hand piece (202). Likewise,accelerometer (208) may be positioned in hand piece (202) to monitor themotion of hand piece (202) as surgical instrument (200) moves throughtissue. Other suitable variations may be utilized as would be apparentto one of ordinary skill in the art in view of the teachings herein.

Microphone (210) is operable generally to act as an acoustic sensor. Itshould be understood that microphone (210) may be operable to detectacoustic signals at ultrasonic frequencies, auditory frequencies, and/orinfrasonic frequencies. Microphone (210) in communication with acomputing module (214), which will be discussed further below, isoperable to detect and record sound samples of anything that might beoccurring around microphone (210). For example, as surgical instrument(200) is used, it will be appreciated that parts of surgical instrument(200) may produce various acoustic signals or impulses able to indicateinformation regarding the nature and/or density of tissue coming incontact with surgical instrument (200). These acoustic signals orimpulses may be received by microphone (210) between production ofvarious acoustic signals or impulses; and/or may be received byalternate microphones. One example may be in the case where surgicalinstrument (200) guides end effector (204) through tissue of differentdensities, surgical instrument (200) may produce different acousticsignals based on various dampening levels or measured loss of signalstrength caused by the tissue. Microphone (210) could be positioned tomonitor acoustic signals at a blade or waveguide in communication withend effector (204). The type/density of tissue encountered by theultrasonic blade may alter acoustic signal properties associated withthe acoustic assembly that includes the blade. Such changes may occur atultrasonic frequencies, auditory frequencies, and/or infrasonicfrequencies. Thus, inferences on tissue density and/or type may be drawnbased on the acoustic signals monitored, which may thereby provideinformation to the user about the type of tissue being affected bysurgical instrument (200).

As noted above, microphone (210) may be operable to monitor sounds atvarious particular frequencies (e.g., ultrasonic frequencies, auditoryfrequencies, and/or infrasonic frequencies, etc.). For example,microphone (210) could be used in communication with various filters,amplifiers, etc. to focus on signals occurring at particularfrequencies, thus avoiding some acoustic signals which may not provideuseful information regarding surgical instrument (200). A Fast FourierTransform (FFT) or other similar computational technique could beapplied to the microphone signal to interoperate one or more frequenciesbeing emitted from the transducer/blade resonant structure. The changein these frequencies can be used as a proxy to modal coupling andtherefore as a means of detecting undesirable vibrational states ormodes. Once detected, this could be used as a means of feedback to alertthe user, change the behavior of the resonant system by altering thedrive signal characteristics, or both. Still other suitable ways inwhich one or more microphones (210) may be used to detect tissue densityand/or changes in tissue density will be apparent to those of ordinaryskill in the art in view of the teachings herein.

Sensor (212) may include, among other things, an impedance sensor, atemperature sensor, a force sensor, and/or any other suitable type ofsensor as would be apparent to one of ordinary skill in the art in viewof the teachings herein. In versions where sensor (212) includes animpedance sensor, sensor (212) may be used to sense the impedance oftissue contacting end effector (204). The impedance of tissueencountered by end effector (204) may vary based on the density of suchtissue. For instance, a relatively dense tissue (e.g., scar tissue) mayexhibit relatively high impedance as compared to impedance exhibited bya less dense tissue (e.g., fat tissue). Thus, sensor (212) may be usedto detect changes in tissue density as a function of impedance. Itshould be understood that such impedance may include electricalimpedance and/or acoustic impedance. For instance, relatively densetissue may exhibit both relatively high electrical impedance andrelatively high acoustic impedance. It should also be understood thatimpedance may be measured in different ways. By way of example only, ananalog circuit may be used to measure average electrical impedance bycreating two voltages that are proportional to the voltage and currentamplitudes (e.g., rms, peak-to-peak, or simple average) and thendividing these voltages to provide an analog voltage output that isproportional to electrical impedance. As another merely illustrativeexample, electrical impedance may be read and calculated digitally andinstantaneously. In particular, a system may read real instantaneousvoltage and real instantaneous current; then divide these values tocalculate the instantaneous impedance. Various suitable ways in which anelectrical impedance sensor may be implemented as sensor (212) will beapparent to those of ordinary skill in the art in view of the teachingsherein. Similarly, various suitable ways in which an acoustic impedancesensor may be implemented as sensor (212) will be apparent to those ofordinary skill in the art in view of the teachings herein.

As another merely illustrative example, different tissue densities maypresent different thermal responses to end effector (204). Accordingly,in versions where sensor (212) includes a temperature sensor, sensor(212) may be used to detect changes in tissue density as a function oftemperature. In versions where sensor (212) comprises a force sensor(e.g., a strain gauge, etc.), sensor (212) may be used to detect changesin tissue density as a function of force/strain encountered by endeffector (204) as end effector (204) bears against the tissue. Stillother suitable types of sensors (212) that may be used to detect tissuedensity and/or changes in tissue density will be apparent to those ofordinary skill in the art in view of the teachings herein.

Accelerometer (208) is operable to detect the motion of end effector(204). It will be appreciated that information gathered fromaccelerometer (208) may be used to determine the force with which endeffector (204) moves. It will also be appreciated that a raw speed,relative speed, average speed, rate of change, or any other suitablemetric associated with movement of end effector (204) may be determined.As end effector (204) encounters relatively dense tissue, this may causeend effector (204) to decelerate along its path of movement, andaccelerometer (208) may be able to detect this deceleration. Similarly,end effector (204) may experience acceleration as it transitions fromdense tissue to less dense tissue along its path of travel, withaccelerometer (208) being able to detect this acceleration. Computingmodule (214) may also be able to differentiate betweenaccelerations/decelerations that are based on changes in tissue densityversus accelerations/decelerations that are based on changes in handmovements of the surgeon. For instance, computing module (214) may beable to compare data from accelerometer (208) with data from some othertype of sensor (e.g., a strain gauge in handle assembly (202), etc.) todistinguish between accelerations/decelerations that are based onchanges in tissue density versus accelerations/decelerations that arebased on changes in hand movements of the surgeon. Still other suitableways in which one or more accelerometers (208) may be used to detecttissue density and/or changes in tissue density will be apparent tothose of ordinary skill in the art in view of the teachings herein.

A power source (206) is also in communication with handle assembly (202)and operable to deliver power to end effector (204). While theillustrated version shows power source (206) separate from handleassembly (204), power source (206) may be integrated into handleassembly (204).

Additionally, surgical instrument (200) comprises computing module(214), which is in communication with end effector (204), power source(206), accelerometer (208), microphone (210), and sensor (212).Computing module (214) may comprise any suitable components, which mayinclude a processor, a memory, or any other suitable computing relatedcomponents as will be apparent to one of ordinary skill in the art inview of the teachings herein. Computing module (214) is operable toexecute or run programs or algorithms regarding the operation of any ofthe components of surgical instrument (200). For example, computingmodule (214) may be operable to control the actions of end effector(204) or of microphone (210), sensor (212), and accelerometer (208).Furthermore, computing module (214) may be in communication with powersource (206) through handle assembly (204), such that computing module(214) is operable to control or utilize power source (206) to carry outany suitable routines and/or programs of computing module (214).Computing module (214) is thus operable to execute control logic.

While computing module (214) is depicted as being positioned withinhandle assembly (202), it will be appreciated that computing module(214) may be located in any suitable position. For example, computingmodule (214) may be positioned in end effector (204), in power source(206), and/or may even be contained within a module located in betweenhandle assembly (202) and power source (206). In yet other exemplaryversions, it will be appreciated that computing module (214) need not belimited to a single computing module (214). Computing module (214) maybe configured such that a plurality of computing modules (214) are usedwhere the plurality of computing modules (214) may be located in asingle location or spread out across surgical instrument (200) or evenremotely located.

As mentioned earlier, end effector (204) comprises a microphone (210),sensor (212), and accelerometer (208). It will further be appreciatedthat using end effector (204) in a surgical procedure may involveproviding ultrasonic vibrations through end effector (204) to thesurgical site. It will further be understood that delivering ultrasonicvibrations to a surgical site results in a tone or pitch produced by endeffector (204). For example, if the vibrations are delivered from endeffector (204) by an ultrasonic blade (e.g. like blade (82) describedabove), it will be understood that as the blade of end effector (204)travels through different types of tissue densities, vibrations from endeffector (204) will produce acoustically distinct sounds since thevibrations travel at different speeds through different densities oftissue. As a result, not only are the sounds produced by the vibrationsthrough different tissue different, it will also be appreciated thatmicrophone (210) is operable to detect the differences in sound for whenvibrations are delivered to different densities of tissue. Thesedifferences in sound can be picked up by blade (82) itself andcomponents in acoustic communication with blade (82) and/or thewaveguide. It will further be appreciated that end effector (204) may beable to deliver vibrations of different frequencies and microphone (210)may monitor acoustic signals at different frequencies. For example, bymonitoring the acoustic signals at different frequencies, different datamay be ascertainable. In some instances, certain changes in tissuedensity may be more pronounced or detectable at certain frequencies.

IV. Exemplary Methods of Using Surgical Instrument

FIG. 4 shows one exemplary method of using surgical instrument (200).Block (400) involves the user turning on surgical instrument (200). Itwill be appreciated that in some versions, surgical instrument (200) maynot need to be necessarily turned on—it may default to an “on” state.

Block (410) comprises beginning acoustic monitoring. In some versions,surgical instrument (200) may be continually monitoring an acousticsignal associated with the acoustic drivetrain (e.g., ultrasonictransducer, horn, waveguide, and ultrasonic blade) of surgicalinstrument (200). It will be appreciated that acoustic monitoring may becarried out using microphone (210) in communication with computingmodule (214). Microphone (210) continually detects the audio signalassociated with the acoustic drivetrain of surgical instrument (200).Computing module (214) continually receives data representing the audiosignal picked up by microphone (210). It will be appreciated thatacoustic monitoring may be carried out using computing module (214)while computing module (214) receives the acoustic signal. Block (420)involves the user using surgical instrument (200) at a surgical site,manipulating tissue with end effector (204). During use, block (430)continually monitors the acoustic signal to determine whether theacoustic signal exceeds a particular predetermined threshold, which canbe continually updated and calculated via computing module (214).

While the present disclosure often uses the term “threshold,” it iscontemplated that this may include a minimum value or floor. In otherwords, a phrase such as “exceeding a threshold” or “exceeds athreshold,” etc. as used herein may be read to also encompass situationswhere a value falls below a predetermined minimum value or floor incertain settings. Thus, with block (430) monitoring to determine whetherthe acoustic signal exceeds a particular predetermined threshold, itshould be understood that this may include monitoring whether theacoustic signal falls below a predetermined minimum value or floor. Itwill also be appreciated that certain changes in acoustic signal (e.g.,exceeding a threshold) may be indicative of a change in tissue density,which may indicate a change in tissue type. Therefore, once user isnotified of the change in block (440), the user can then either stopusing surgical instrument (200), continue to use surgical instrument(200), or modify the use of surgical instrument (200).

There are numerous ways in which the method depicted in FIG. 4 may becarried out, including various ways in which block (430) may be carriedout. For instance, some versions of computing module (214) along withthe various sensors (210, 212, 208) of end effector (204) are operableto have two monitoring modes: a transverse monitoring mode and a tissuedensity monitoring mode. In the transverse monitoring mode, computingmodule (214) is operable to perform fast Fourier transforms on acousticsamples to identify their transverse modes and associated frequencies.Computing module (214) is further operable to establish baseline modalspacing of a plurality of samples and their associated frequenciesbefore surgical instrument (200) is used on tissue, when end effector(204) is under no load. Once a load is applied to end effector (204)during use of surgical instrument (200) in a surgical procedure,computing module (214) is operable to compare identified transversemodes to the baselines. Finally, in the event that a sensed traversemode signal exceeds a certain threshold or falls below a floor duringuse of surgical instrument (200) in a surgical procedure, computingmodule (214) may be operable to shut down the operation of anytransducers associated with surgical instrument (200) or otherwiserender end effector (204) at least partially inoperable for at least aperiod of time.

In tissue density monitoring mode, computing module (214) is alsooperable to perform fast Fourier transforms on acoustic samples toidentify their amplitudes at different frequencies. Computing module(214) is further operable to establish baseline amplitudes of aplurality of samples and their associated frequencies before surgicalinstrument (200) is used on tissue, when end effector (204) is under noload. Once a load is applied to end effector (204) during use ofsurgical instrument (200) in a surgical procedure, computing module(214) is operable to compare the sensed amplitude at each frequencyagainst the pre-established baselines. Finally, in the event that theamplitude of measured frequencies drop below a predetermined range,computing module (214) is operable to convey that potentially densetissue is being encountered by end effector (204). For instance,computing module (214) may communicate to an indicator that visuallyand/or audibly alerts the user that dense tissue has been encountered.Once the amplitude returns to the baseline range, then computing module(214) may communicate to the indicator to either stop alerting the useror produce a different visual and/or audible alert for the user. Inaddition or in the alternative to alerts, computing module (214) mayaffect operational characteristics of end effector (204) in response tochanges in tissue density. Of course, other suitable uses andcapabilities for computing module (214) will be apparent to one ofordinary skill in the art in view of the teachings herein.

FIG. 5 shows another exemplary method of using surgical instrument(200). It will be appreciated that in some circumstances, surgicalinstrument (200) may be used in the application of abdominoplasty, bodycontouring of fatty tissue, and/or some other procedure where scartissue or other dense tissue may be encountered. It will be appreciatedthat more current may be desirable for use with surgical instrument(200) such that scar tissue can be cut without the user noticing achange in performance of surgical instrument (200). Accordingly, block(500) shows surgical instrument (200) being turned on. Thereafter, block(510) involves beginning monitoring of tissue impedance and/or force.Impedance monitoring may be accomplished using, for example, sensor(212) of FIG. 3, which may comprise an impedance sensor configured tosense the impedance of tissue encountered by end effector (204).Furthermore, force may be measured using accelerometer (208) inconjunction with computing module (214) to sense the amount of physicalresistance presented by tissue against end effector (204). While theillustrated version shows tissue impedance and/or force being monitored,it will be understood that microphone (210) may be used in addition toor in the alternative in order to monitor acoustic signals of surgicalinstrument (200). Block (520) then shows the user using surgicalinstrument (200) in a surgical procedure. During the procedure, block(530) monitors sensed impedance and force to determine whether impedanceor force exceeds any particular threshold (or falls below any particularfloors). In the event that either occurs, block (540) directs surgicalinstrument (200) to increase current through use of power source (206),thereby driving end effector (204) with greater power.

It will also be appreciated that current may be increased in response tochanges in acoustic signals monitored by microphone (210). For example,a highly dampened acoustic signal may be indicative of denser tissue,which surgical instrument (200) would respond to with an increase incurrent. A feedback loop is created with block (550), where block (550)monitors to determine if impedance and/or force have dropped below thepredetermined threshold after increasing the current in block (540).Thus, in the event that tough scar tissue is encountered by end effector(204), current will be continually increased in order to provide asmooth cutting experience to the surgeon. In the event that impedancelevels, force levels, and/or acoustic signals drop back down below thepredetermined threshold, then block (560) reduces current back to thelevel previously used at block (520).

It should be understood that selected threshold values may be dependenton several factors, including but not limited to the combination oftransducer and type of end effector (204) being used, the usage habitsand proficiency of the user, the type of surgical procedure beingperformed, and patient to patient variation in tissue. Initialthresholds may be established based on any single factor or combinationof factors. In some instances, the type of end effector will be thedominant factor and this may be used in the initial setting of thethreshold. This initial threshold setting may then be adjusted based onother factors. For instance, a surgeon may identify himself/herself byname and/or by entering a code that is specific to their instrument useprofile. It should also be understood that the system may be a learningsystem where the threshold starts at a certain initial setting and isadjusted as the surgeon uses the system. In some such instances, thesurgeon may start with relatively easy tissue (e.g., providing datavalues below the threshold) then transition to tougher tissue as theprocedure progresses. This early use of instrument (200) may be used toeffectively baseline the threshold early in the procedure and then allowthe threshold to adjust up/down according to predetermined maximum andminimum range limits. Other suitable ways in which threshold values maybe established will be apparent to those of ordinary skill in the art inview of the teachings herein.

It will be appreciated that in scenarios such as applications wheresurgical instrument (200) is used to remove tissue from bone, it may bedesirable to avoid inadvertently cutting bone in the process of removingsoft tissue. Accordingly, rather than increasing current in response toa change in tissue density as was shown in FIG. 5, current may insteadbe decreased. To that end, block (600) of FIG. 6 shows surgicalinstrument (200) being turned on. Block (610) shows beginning monitoringof impedance and force. Accelerometer (208), for example, may be used todetect slowing or stopping of movement of end effector (204) throughtissue. Sensor (212) may also comprise an impedance sensor used tomonitor impedance of tissue encountered by end effector (204). Inaddition or in the alternative, block (610) could be used to monitor theacoustic signals of surgical instrument (200) to determine whethercurrent provided to surgical instrument (200) should be decreased. Inblock (620), the user uses surgical instrument (200). Block (630) showschecking and continually monitoring impedance and/or force measurementsto determine whether either exceeds any predetermined threshold values(or falls below any particular floors). Additionally, or in thealternative, block (630) may also monitor acoustic signals. In the eventthat threshold values are exceeded, it may be indicative of surgicalinstrument (200) encountering bone tissue. Thus, in block (640), currentprovided to surgical instrument (200) by power source (206) is reduced,thereby decreasing or stopping power at end effector (204). A feedbackloop with block (650) is formed where block (650) continually monitorsto determine whether impedance, force, and/or acoustic measurements havefallen back below a predetermined threshold. If not, then it isindicative that bone tissue may still be nearby, thus requiring lesscurrent to drive end effector (204). Once it has been determined thatimpedance, force, and/or acoustic measurements have fallen back belowthe threshold amounts, block (660) directs surgical instrument (200) toincrease the current back to the level previously used at block (620).

In some instances, it will be appreciated that rather than havingsurgical instrument (200) adjust to the sensed tissue circumstances, itmay be desirable to have surgical instrument (200) simply notify theuser such that the user can adjust the use of surgical instrument (200).For example, FIG. 7 shows block (700) where surgical device is turnedon. Thereafter, block (710) indicates that tissue impedance monitoringbegins. Tissue impedance monitoring may be accomplished through, forexample, sensor (212) shown in FIG. 3. It will be appreciated that inaddition to or in the alternative, acoustic signals detected throughmicrophone (210) and/or movement detected through accelerometer (208)may be monitored as well. Thereafter, the user may begin cutting asshown in block (720). Block (730) continually monitors the tissueimpedance, force, and/or acoustic signals as detected by sensor (212).In the event that a rapid change in impedance, movement of end effector(204), and/or acoustic signal occurs, block (740) alerts the user. Suchan alert may comprise an audio alert, a visual alert, or any othersuitable alert as would be apparent to one of ordinary skill in the artin view of the teachings herein. The alert (audio, visual, etc.) may beintegrated into handpiece (202) or even power source (206), such thatthe user may be alerted by noticing the alert occurring on handpiece(202). In addition or in the alternative, the alert device may benoticeable from power source (206) or any other suitable locationvisually perceivable by the user or within earshot of the user if thealert device includes an audio alert. In block (750), the user may thenalter the movement or positioning of surgical instrument (200) andthereafter continue to cut tissue as shown in block (760). For instance,the user may move end effector (204) in a reciprocating “hacksaw motion”in order to more effectively transect dense tissue. As the user movesend effector (204) through dense tissue, once the tissue becomes lessdense, an alert may be provided to the user indicating that the regionof dense tissue has been passed. As a result, the user may revert tousing the motion for moving end effector (204) prior to thereciprocating “hacksaw motion.” In the alternative, the user may changehis or her motion of end effector (204) to any suitable motion as wouldbe apparent to one of ordinary skill in the art in view of the teachingsherein.

It will be appreciated that in some versions, surgical instrument (200)may need to be more flexible in the manner in which current is managed.Instead of exclusively increasing current or decreasing current, it maybe desirable to use surgical instrument (200) in a manner where surgicalinstrument (200) can intelligently determine whether an increase incurrent or a decrease in current is necessary based on tissue density orchanges in tissue density that end effector (204) engages. For example,in FIG. 8, block (800) involves turning on surgical instrument (200).Block (810) begins energy pulses and use of surgical instrument (200).In the case of an ultrasonic surgical instrument (50), surgicalinstrument (50) may deliver ultrasonic vibrations through blade (82) tothe surgical site. Such vibrations may be produced by pulsing electricalpower to a transducer of surgical instrument (50). In some versions, anactivation pulse is delivered to transducer (100) with a frequencyranging from one pulse every 10 milliseconds to one pulse every 100milliseconds. Of course, any other suitable pulse frequency may be usedas will be apparent to those of ordinary skill in the art in view of theteachings herein. These activation pulses cause piezoelectric elementsin transducer (100) to convert the electrical power into mechanicaloscillatory/vibrational power, resulting in ultrasonic oscillations thatare communicated along an acoustic waveguide to ultrasonic blade (82).Between the electrical activation pulses delivered to transducer (100)to produce ultrasonic vibrations, surgical instrument (50) provides avoltage to sensor (212) to detect the impedance of adjacent tissue. Inthe event that high impedance is detected as shown in block (830),current may be increased in the next power delivery pulse as shown inblock (860) in order to assist surgical instrument (200) in cuttingthrough relatively dense tissue at the surgical site. In the event thatlow impedance is detected as shown in block (840), current delivered tosurgical instrument (200) in the next power delivery pulse may bemaintained or lowered as shown in block (850). It will be appreciatedthat maintained current levels may be approximately 250 mA or any othersuitable current level as would be apparent to one of ordinary skill inthe art in view of the teachings herein.

In some instances, it may be desirable to determine if surgical tissueis positioned in fatty tissue or muscle tissue. It will be appreciatedthat the acoustic drivetrain (e.g., ultrasonic transducer, horn,waveguide, and ultrasonic blade) of surgical instrument (200) mayexhibit a different resonant frequency based on whether end effector(204) is in contact with tissue such as fatty tissue versus relativelydenser tissue such as muscle, which places a greater acoustic load onend effector (204). For instance, a low load such as fatty tissue mayprovide a relatively smaller shift in resonant frequency of the acousticdrivetrain when end effector (204) bears against the fatty tissue.Denser tissue such as muscle or cartilage may provide a highermechanical/acoustic load against end effector (204), resulting in arelatively larger in resonant frequency of the acoustic drivetrain.These effects may be even more pronounced when end effector (204) isused as a blade instead of a shear. When end effector (204) is used as ablade, the user may determine the effective load based on the selectedtissue type and the amount of pressure applied by the bladed endeffector (204) against the tissue. The higher the force or pressure ofapplication, the higher the acoustic load and the greater the shift inresonant frequency. When end effector (204) is used as a shear (e.g.,through action by a clamping feature like clamp arm (84), etc.), thepressure profile may be less dependent on the amount/type of tissuebetween the clamping feature and the ultrasonic blade. This may enablethe user to focus more on which tissue to transect and less on thenuances of the application of force to various types of tissue. In somesuch versions, the user may effect faster transaction times by liftingthe ultrasonic blade edge into the tissue, with force sensors (212)providing measurement of pressure between the ultrasonic blade andclamping member at end effector (204).

An example of processing changes in resonant frequency is shown in FIG.9. Block (900) shows turning on surgical instrument (200). Block (910)shows determining a resonant frequency, F_(n) followed by setting theinitial frequency to F_(n) _(_) _(start) as seen in block (920). Thisestablishes a baseline resonant frequency for comparison with laterdetected resonant frequencies. It will be appreciated that such abaseline resonant frequency (F_(n) _(_) _(start)) may be obtained byactivating an ultrasonic blade of end effector (204) before applying endeffector (204) against tissue, and sensing forces at end effector (2040with sensor (212). The user may then cut tissue as shown in block (930).As tissue is cut, sensor (212) continues to monitor the resonantfrequency (F_(n)) as seen in block (940). As F_(n) is updated, the rateof change of F_(n) in relation to F_(n) _(_) _(start) is monitored topick up shifts in the resonant frequency. In the event that a slow rateof change of F_(n) is observed, then it can be inferred that surgicalinstrument (200) is in muscle tissue. The user may wish to know thepresence of muscle tissue, thus block (990) provides user feedback,which may be in the form of an audible tone, vibration, or any othersuitable feedback means as would be apparent to one of ordinary skill inthe art in view of the teachings herein. Thereafter, current provided tosurgical instrument (200) is manually or automatically increased asshown in block (995) in response to the sensed tissue density increase,to drive end effector (204) with more energy to transect the relativelydense tissue. In the event that the rate of range of F_(n) is fast asshown in block (960), it can be inferred that surgical instrument (200)is in fatty tissue. Accordingly, current may be manually orautomatically reduced as shown in block (980), to drive end effector(204) with less energy to transect the relatively soft tissue.

It will further be appreciated that in some cases, it may be desirableto have a surgical instrument (200) operable to simultaneously monitorseveral different characteristics including force changes,power/impedance changes, resonant frequency changes, and/or motionchanges to determine whether the density of tissue being cut ischanging. FIG. 10 shows such a system and begins with block (1000) ofthe user turning on surgical instrument (200). The user then usessurgical instrument (200) to cut tissue as shown in block (1010). Assurgical instrument (200) is being used, force, acceleration, power,impedance, and acoustic signal levels and curves are being continuouslymonitored as shown in block (1020). Thereafter any increases in force asseen in block (1030) may be detected. Furthermore, increases in power asseen in block (1040) may be detected, and any decreases in motion asseen in block (1050) may be detected as well. Accordingly, currentand/or power may be adjusted accordingly (increased or decreased) asshown in block (1060). For instance, block (1060) and/or block (1070)may be based on discrete values and/or trends based on variouscombinations of values and/or trends occurring and detected in any ofblocks (1030, 1040, 1050). It will be appreciated that particularcombinations of impedance values/trends and acoustic signals may beindicative of particular tissue density characteristics. Likewise,combinations of particular accelerometer values and acoustic signals maybe indicative of another tissue density characteristic. It will beunderstood that various combinations of impedance, acoustic signals,and/or accelerometer readings may be used to indicate characteristics oftissue density, which may be programmed or otherwise integrated intocomputing module (214). Then accordingly, computing module (214) may beoperable to provide corresponding instructions and/or orders at blocks(1060, 1070) to enable end effector (204) to continue to traverse thetissue.

Surgical instrument (200) may also be operable to specifically identifythe tissue type based on monitoring in blocks (1030, 1040, 1050) and toalert the user accordingly. For example, the user may be informed thatend effector (204) is engaging bone, based on a particular combinationof acoustic, impedance, and/or force signals. Other combinations ofsignals may be used to indicate that the tissue being engaged is fattytissue, scar tissue, etc. Thereafter, audible feedback shown in block(1070) may be provided to the user to inform the user of any tissuedensity change. It will also be appreciated that other feedbackmechanisms such as visual feedback, tactile feedback, and/or endeffector (204) control modifications may be used in addition to or inlieu of audible feedback, as will be apparent to one of ordinary skillin the art in view of the teachings herein. Furthermore, it will beappreciated that the methods discussed are merely exemplary and othersuitable methods may be used as would be apparent to one of ordinaryskill in the art.

In some instances where surgical instrument (200) is used through atrocar or other access port (e.g., in minimally invasive surgery), theshaft of surgical instrument (200) may be moved in a pivotal fashionabout the entry point of the trocar in the patient. It should beunderstood that the entry point of the trocar in the patient may thusact as a virtual center of motion. Motion measured at handle assembly(202) may be proportional to the relative fulcrum (length of instrument(200) inside the patient's body/length of instrument (200) outside thepatient's body). Motion, force, acceleration, etc. measured at endeffector (204) may relate directly to tissue effect. Sensors located inhandle assembly (202) may need to be scaled to reflect the pivot-fulcrumrelationships in order to accurately represent what is happening at theinterface of end effector (204) and tissue. This and other suitable waysto account for usage of instrument (200) through a trocar or otheraccess port in a patient will be apparent to those of ordinary skill inthe art in view of the teachings herein.

V. Miscellaneous

While examples above relate to surgical instrument (10) in the form ofan ultrasonic instrument, it should be understood that the teachingsherein may be readily applied to various types of electrosurgicalinstruments, including but not limited to those taught in U.S. Pat. No,6,500,176 entitled “Electrosurgical Systems and Techniques for SealingTissue,” issued Dec. 31, 2002, the disclosure of which is incorporatedby reference herein; U.S. Pat. No. 7,112,201 entitled “ElectrosurgicalInstrument and Method of Use,” issued Sep. 26, 2006, the disclosure ofwhich is incorporated by reference herein; U.S. Pat. No. 7,125,409,entitled “Electrosurgical Working End for Controlled Energy Delivery,”issued Oct. 24, 2006, the disclosure of which is incorporated byreference herein; U.S. Pat. No. 7,169,146 entitled “ElectrosurgicalProbe and Method of Use,” issued Jan. 30, 2007, the disclosure of whichis incorporated by reference herein; U.S. Pat. No. 7,186,253, entitled“Electrosurgical Jaw Structure for Controlled Energy Delivery,” issuedMar. 6, 2007, the disclosure of which is incorporated by referenceherein; U.S. Pat. No. 7,189,233, entitled “Electrosurgical Instrument,”issued Mar. 13, 2007, the disclosure of which is incorporated byreference herein; U.S. Pat. No. 7,220,951, entitled “Surgical SealingSurfaces and Methods of Use,” issued May 22, 2007, the disclosure ofwhich is incorporated by reference herein; U.S. Pat. No. 7,309,849,entitled “Polymer Compositions Exhibiting a PTC Property and Methods ofFabrication,” issued Dec. 18, 2007, the disclosure of which isincorporated by reference herein; U.S. Pat. No. 7,311,709, entitled“Electrosurgical Instrument and Method of Use,” issued Dec. 25, 2007,the disclosure of which is incorporated by reference herein; U.S. Pat.No. 7,354,440, entitled “Electrosurgical Instrument and Method of Use,”issued Apr. 8, 2008, the disclosure of which is incorporated byreference herein; U.S. Pat. No. 7,381,209, entitled “ElectrosurgicalInstrument,” issued Jun. 3, 2008, the disclosure of which isincorporated by reference herein; U.S. Pub. No. 2011/0087218, entitled“Surgical Instrument Comprising First and Second Drive SystemsActuatable by a Common Trigger Mechanism,” published Apr. 14, 2011, nowU.S. Pat. No. 8,939,974, issued on Jan. 27, 2015, the disclosure ofwhich is incorporated by reference herein; and U.S. Pat. App. No.13/151,481, entitled “Motor Driven Electrosurgical Device withMechanical and Electrical Feedback,” filed Jun. 2, 2011, and publishedMay 10, 2012 as U.S. Pat. Pub. No. 2012/0116379, now U.S. Pat. No.9,161,803, issued on Oct. 20, 2015, the disclosure of which isincorporated by reference herein.

Furthermore, the teachings herein may be readily applied to varioustypes of electrically powered cutting and stapling instruments,including but not limited to those taught in U.S. Pat. No. 7,416,101entitled “Motor-Driven Surgical Cutting and Fastening Instrument withLoading Force Feedback,” issued Aug. 26, 2008, the disclosure of whichis incorporated by reference herein; U.S. Pub. No. 2009/0209979,entitled “Motorized Cutting and Fastening Instrument Having ControlCircuit for Optimizing Battery Usage,” published Aug. 20, 2009, now U.S.Pat. No. 8,662,274, issued on Jan. 7, 2014; and U.S. Pat. App. No.13/151,481, entitled “Motor Driven Electrosurgical Device withMechanical and Electrical Feedback,” filed Jun. 2, 2011, and publishedMay 10, 2012 as U.S. Pat. Pub. No. 2012/0116379, now U.S. Pat. No.9,161,803, issued on Oct. 20, 2015, the disclosure of which isincorporated by reference herein. Still other suitable types of devicesto which the teachings herein may be applied will be apparent to thoseof ordinary skill in the art.

It should be appreciated that any patent, publication, or otherdisclosure material, in whole or in part, that is said to beincorporated by reference herein is incorporated herein only to theextent that the incorporated material does not conflict with existingdefinitions, statements, or other disclosure material set forth in thisdisclosure. As such, and to the extent necessary, the disclosure asexplicitly set forth herein supersedes any conflicting materialincorporated herein by reference. Any material, or portion thereof, thatis said to be incorporated by reference herein, but which conflicts withexisting definitions, statements, or other disclosure material set forthherein will only be incorporated to the extent that no conflict arisesbetween that incorporated material and the existing disclosure material.

Versions of the present invention have application in conventionalendoscopic and open surgical instrumentation as well as application inrobotic-assisted surgery. An exemplary robotic-assist surgery system isdisclosed in U.S. Pat. No. 6,783,524, entitled “Robotic Surgical Toolwith Ultrasound Cauterizing and Cutting Instrument,” published Aug. 31,2004, the disclosure of which is incorporated by reference herein.

Versions of the devices disclosed herein can be designed to be disposedof after a single use, or they can be designed to be used multipletimes. Versions may, in either or both cases, be reconditioned for reuseafter at least one use. Reconditioning may include any combination ofthe steps of disassembly of the device, followed by cleaning orreplacement of particular pieces, and subsequent reassembly. Inparticular, versions of the device may be disassembled, and any numberof the particular pieces or parts of the device may be selectivelyreplaced or removed in any combination. Upon cleaning and/or replacementof particular parts, versions of the device may be reassembled forsubsequent use either at a reconditioning facility, or by a surgicalteam immediately prior to a surgical procedure. Those skilled in the artwill appreciate that reconditioning of a device may utilize a variety oftechniques for disassembly, cleaning/replacement, and reassembly. Use ofsuch techniques, and the resulting reconditioned device, are all withinthe scope of the present application.

By way of example only, versions described herein may be processedbefore surgery. First, a new or used instrument may be obtained and ifnecessary cleaned. The instrument may then be sterilized. In onesterilization technique, the instrument is placed in a closed and sealedcontainer, such as a plastic or TYVEK bag. The container and instrumentmay then be placed in a field of radiation that can penetrate thecontainer, such as gamma radiation, x-rays, or high-energy electrons.The radiation may kill bacteria on the instrument and in the container.The sterilized instrument may then be stored in the sterile container.The sealed container may keep the instrument sterile until it is openedin a surgical facility. A device may also be sterilized using any othertechnique known in the art, including but not limited to beta or gammaradiation, ethylene oxide, or steam.

Having shown and described various versions of the present invention,further adaptations of the methods and systems described herein may beaccomplished by appropriate modifications by one of ordinary skill inthe art without departing from the scope of the present invention.Several of such potential modifications have been mentioned, and otherswill be apparent to those skilled in the art. For instance, theexamples, versions, geometrics, materials, dimensions, ratios, steps,and the like discussed above are illustrative and are not required.Accordingly, the scope of the present invention should be considered interms of the following claims and is understood not to be limited to thedetails of structure and operation shown and described in thespecification and drawings.

We claim:
 1. An apparatus comprising: (a) an end effector configured foruse in a surgical procedure, wherein the end effector comprises anultrasonic blade coupled to an acoustic drivetrain, the acousticdrivetrain comprising an ultrasonic transducer, wherein the end effectoris configured to deliver ultrasonic energy to a surgical site via theultrasonic blade; (b) a body assembly in communication with the endeffector; (c) a power source, wherein the power source is operable todeliver a current to the ultrasonic transducer in order to power theultrasonic blade; and (d) a control module, wherein the control moduleis configured to determine a first resonant frequency associated withthe acoustic drivetrain, wherein the control module is furtherconfigured to determine a shift from the first resonant frequency to asecond resonant frequency associated with the acoustic drivetrain,wherein the control module is operable to change the current deliveredfrom the power source to the ultrasonic transducer based on the shiftfrom the first resonant frequency to the second resonant frequency. 2.The apparatus of claim 1, further comprising at least one sensor,wherein the at least one sensor comprises a microphone capable ofperforming one or more of transmitting, receiving, or measuring sound.3. The apparatus of claim 2, wherein the microphone is configured tosense ultrasonic, auditory, or infrasonic vibrations associated with aunique modal coupling of the ultrasonic blade in an activated state. 4.The apparatus of claim 1, further comprising at least one sensor,wherein the at least one sensor comprises an impedance sensor.
 5. Theapparatus of claim 4, wherein the impedance sensor is configured tosense electrical impedance associated with tissue.
 6. The apparatus ofclaim 1, wherein the end effector is operable to produce differentacoustic signals based on the density of tissue proximate to orencountered by the ultrasonic blade.
 7. The apparatus of claim 1,further comprising an audible feedback device in communication with thecontrol module.
 8. The apparatus of claim 1, further comprising atactile feedback device in communication with the control module.
 9. Theapparatus of claim 1, further comprising at least one sensor, whereinthe at least one sensor comprises an accelerometer.
 10. The apparatus ofclaim 1, further comprising at least one sensor, wherein the controlmodule is configured to notify the user of changes detected by the atleast one sensor.
 11. The apparatus of claim 1, further comprising atleast one sensor, wherein the at least one sensor comprises a pluralityof sensors configured to monitor different physical attributes.
 12. Theapparatus of claim 1, wherein the control module is programmable to haveat least one predefined threshold parameter.
 13. The apparatus of claim1, wherein the control module is configured to perform simultaneousimpedance and force monitoring.
 14. The apparatus of claim 1, furthercomprising at least one sensor, wherein the control module is configuredto increase power to the end effector in response to data from the atleast one sensor indicating an increase in tissue density.
 15. A methodof detecting a change in tissue density using a surgical device havingan end effector, an ultrasonic blade, at least one sensor, and acomputing module, wherein the ultrasonic blade is operable to respond toat least one physical characteristic of tissue proximate to orencountered by the ultrasonic blade, the method comprising: (a) turningon the surgical device; (b) processing data from the at least one sensorwith the computing module when the end effector is under no load toestablish a baseline of amplitudes associated with a plurality offrequencies for the ultrasonic blade; (c) processing data from the atleast one sensor with the computing module when the end effector isunder a load to establish a first sample of amplitudes associated withthe plurality of frequencies for the ultrasonic blade; (d) comparing thefirst sample of amplitudes with the baseline of amplitudes associatedwith the plurality of frequencies, wherein the act of comparing thefirst sample of amplitudes with the baseline of amplitudes is performedby the computing module; and (e) simultaneously notifying a user andadjusting one or both of power or surgical technique in response to thecomparison of the first sample of amplitudes with the baseline ofamplitudes associated with the plurality of frequencies exceeding athreshold value, wherein the act of simultaneously notifying a user andadjusting one or both of power or surgical technique in response to thecomparison is performed by the computing module.
 16. The method of claim15, wherein the act of adjusting comprises varying a current output tothe end effector if the monitored physical characteristic exceeds athreshold value.
 17. A method of detecting changes in tissue densityusing a surgical instrument with a computing module, an end effector,and a power supply, the method comprising: (a) actuating the endeffector, wherein the act of actuating the end effector produces aresonant frequency within at least a portion of the end effector; (b)determining an initial value for the resonant frequency; (c) using thesurgical instrument; (d) monitoring a rate of change of the resonantfrequency within the end effector; (e) determining if the rate of changedeviates beyond a predetermined value; and (f) altering the amount ofcurrent produced by the power supply if the rate of change deviatesbeyond the predetermined value.
 18. The method of claim 17, wherein theend effector comprises an ultrasonic blade, wherein the act of actuatingthe end effector comprises activating the ultrasonic blade and engagingthe blade with tissue, wherein the tissue modifies an acoustic signalassociated with the ultrasonic blade, wherein the act of monitoring rateof change of the physical characteristic comprises detecting themodification of the acoustic signal by the tissue.